remove old docker repo

supporting-docs/projects/2014-08-12-synapse.md

@@ -14,7 +14,7 @@ Matrix.org’s reference server – Synapse: [https://github.com/matrix-org/syna
 
 Apt repo: [https://matrix.org/packages/debian/](https://matrix.org/packages/debian/)
 
-Dockerfile from Silvio Fricke: [https://registry.hub.docker.com/u/silviof/docker-matrix/](https://registry.hub.docker.com/u/silviof/docker-matrix/) – also hosted on [https://github.com/matrix-org/docker-matrix](https://github.com/matrix-org/docker-matrix)
+Dockerfile from Silvio Fricke: [https://registry.hub.docker.com/u/silviof/docker-matrix/](https://registry.hub.docker.com/u/silviof/docker-matrix/)
 
 ArchLinux package from Ivan Shapovalov: [https://www.archlinux.org/packages/community/any/matrix-synapse/](https://www.archlinux.org/packages/community/any/matrix-synapse/)